Aircraft



Feb. 18, 1936. J. H. cRosMAN, 3D

AIRCRAFT Filed Feb. 28. 1935 CFI Patented Feb. 18, 1936 TES PATET AIRCRAFT Application February 28, 1935, Serial No. 8,740

5 Claims.

This invention relates to aircraft and has for its object to reduce air resistance to the forward movement of aircraft, whereby the speed of the same, at a given nunber of revolutions per minute of the propeller, may be materially increased, or the number of revolutions to maintain a given speed may be decreased. In U. S. Patent No. 1,922,124, granted me August l5, 1933, is set forth a construction having the same general object in View, and the specic object of the present invention is to decrease the resistance of the air to the forward movement of Vthe plane and at the same time secure a reduction in temperature in certain parts of the mechanism to the rear of the propeller. In the operation of the construction set forth in my said patent it has been found that while a very material increase in the speed of the aircraft at a given number of revolutions of the propeller is secured, there also occurs a rise in temperature in certain parts of the mechanism to the rear of the propeller which it is desirable to avoid, and the present invention is designed to accomplish this result.

According to the invention set forth in said patent, two reversely curved longitudinally extending portions of a hollow cone, one element of which cone is perpendicular to its base, were joined along said perpendicular element and connected in any suitable manner to the forward end of the propeller shaft. A cross section of these two connected cone portions was in the general shape of the letter S, and these two sections were sc mounted upon and forward of the hub of the propeller that when the propeller was revolved to move the airplane forward, the free edges of said cone portions were the leading portions. Moreover, the cone portions were such that the base of the cone and the apex thereof were connected by a straight line. According to the present invention, the hollow cone sections are portions of a cone which is more sharply turned inward near its apex than along the base portions thereof, thus affording an increased operating service over what would be attained if the sections were those of a regular cone, in which the surface extended in a straight line from the base of the apex to the cone.

The inventive idea is illustrated in the accompanying drawing, but it is to be expressly understood that such drawing is for the purpose of illustration only and is not designed to dene the limits of the invention, reference being had to the appended claims for that purpose.

` pass.

(Cl. Mtl- 159) of an airplane propeller embodying the present invention;

Fig. 2 is a plan view, partly in section, showing one means of attaching the present invention to a propeller shaft;

Fig. 3 an enlarged plan view; 5

Fig. 4 is a front elevation of Fig. 3, and

Fig. 5 is a section on the lin-e 5 5 of Fig. 3.

Referring to the drawing in which like reference numerals indicate like parts throughout the several views, l is a propeller shaft here shown as having a forward flange 2 to which the propeller 3 is secured, as by bolts 4 4, the direction of revolution of the propeller being indicated by arrows on the vanes of the propeller in Fig. 1. 5 5' are sections of a hollow cone, one element of which cone is perpendicular to its base.

The two cone sections 5 5 are connected together along this vertical element as shown at 6 in Fig. 1, the cone portions being so connected that a cross section taken through the two portions will be in the form of a reversed letter S. Preferably the two cone portions are not connected throughout their entire length but are slightly spaced apart near their apex, as indi- 25 cated at l, and preferably also the cone sections as they approach the apex are sharply inclined inward towards the apex as at 8 8. These two cone sections thus connected are secured in any suitable manner to the forward-face of the hub of the propeller. As here shown, the cone sections at their base are rigidly secured to plate 9 through which the bolts @-4 that are employed to secure the propeller to the propeller shaft also Any other suitable means may be employed for mounting the cone sections to revolve with the propeller, the two cone sections being so secured to the propeller that the outer curved face of each cone section constitutes the leading face thereof when the propeller is reja volvi-ng to move the airplane forward. That is, instead of the free edges lll-l0 being the leading edges, the curved surfaces Il-I l lead, and the free edges Ill-I0 become the following edges, as is clearly indicated by the arrows in Fig. 5, and as will be readily understood by an inspection of Fig. 1, where the arrows adjacent the propeller blades indicate the direction of revolution of the propeller.

By thus combining the reversely curved portions of a hollow cone with the airplane propeller so that the curved portions of the hollow cone sections are in the lead when the propeller is revolved to move the airplane forward, it has been found that not only is there a material increase in the speed of the airplane for a given number of revolutions per minute of the propeller, but

there is also a material decrease in the temperature of the parts of the airplane engine to the rear of the propeller over the temperatures that prevail when using the construction of my aforesaid patent, the decrease in temperature in some instances being as great as 20 F., and this reduction in temperature is a matter of very decided importance in the operation of an airplane motor.

Having thus described the invention, what is claimed is:

1. The combination of a propeller for airplanes, a vertical section of a hollow cone having its base secured to the front face of the hub of said propeller with one of its section lines extending forward at right angle to said face, a second similar vertical section of a hollow cone also having its base secured to the front face of the propeller hub with one of its section lines extending forward at right angles to said face, said two sections being joined along said right angular lines with the outer curved face of each section constituting the leading face thereof when the propeller is revolved to move the airplane forward.

2. The combination of a propeller for airplanes and two reversely-curved vertical sections of a hollow cone joined together along a line extending forward at right angles to the front face of the hub of said propeller and with the outer curved face of each section constituting the leading face thereof when the propeller is revolved to move the airplane forward.

3. The combination of a propeller for airplanes and two reversely curved vertical sections of a hollow cone joined together through a portion of 5 their length only and along a line extending forward at right angles to the front face o-f the hub of said propeller and with the outer curved face of each section constituting the leading face thereof when the propeller is revolved to move the airplane forward.

4. The combination of two reversely-curved vertical sections of the shell of a hollow cone with the front of the hub of a propeller for airplanes,

said sections being united through a portion of their length along a line extending forward from the propeller hub and in line with the axis thereof and with the outer curved face of each cone section constituting the leading face thereof when the propeller is revolved to move the airplane forward.

5. The combination of a, propeller for airplanes, and two reversely-curved vertical sections of a hollow cone which is more sharply coned inward near its apex than along the base portion, said sections being joined together along a portion of their length on a line extending forward from the propeller hub and in line with the axis thereof and with the outer curved face of each cone section constituting the leading face thereof when the propeller is revolved to move the airplane forward.

JAMES HERON CROSMAN, III. 

